Are companies liable for cancer risks of employees' phones?

The International Agency for Research on Cancer (part of the World Health Organisation) says radiation from mobile phone handsets is "possibly carcinogenic". That puts it in the same category as petrol exhausts, lead, creosote and the pesticide DDT.

It follows an important IARC study last year that concluded more than 30 minutes of calls each day over ten years increased the risk of gliomas (tumours that start in the spine or brain) by forty percent. Now it seems there is limited evidence of a possible link with brain tumours too.

The evidence is far from clear, but the warning signs are there. So how can we protect ourselves from these possible risks? And how can companies protect themselves against future liability claims from staff issued with mobile phones?